When Harvard University friends Sheryl Sandberg and Andrew M. Cameron, M.D., Ph.D., met up at their 20th college reunion last spring, they got to talking. Sandberg knew that Cameron, a transplant surgeon at Johns Hopkins, was passionate about solving the perennial problem of transplantation: the critical shortage of donated organs in the United States. And he knew that Sandberg, as chief operating officer of Facebook, had a way of easily reaching hundreds of millions of people.

Talking turned to brainstorming. The result: Starting today, Facebook users can now share their organ donor status with friends and family in the same way they share basic information about where they went to college or who they are married to. The hope is that, by starting a conversation with friends and family through social media, the discussion will go viral, with a critical mass of people educating themselves about the benefits of organ donation and choosing to register as organ donors.

"Doctors save lives one person at a time. Sheryl is able to reach people millions at a time," says Cameron, an associate professor of surgery at the Johns Hopkins University School of Medicine and surgical director of liver transplantation. "We have a public health problem that really just needs education, communication and discussion. It's a great match."

More than 114,000 people are waiting for hearts, livers and kidneys and other organs in the United States. Someone dies every four hours waiting for a transplant. The need for organ donation keeps increasing, while the rate of donation over the past 20 years is almost flat, despite widespread public health campaigns. In surveys, upwards of 90 percent of Americans say they favor organ transplantation, but only 30 percent of the 200 million in the U.S. with driver's licenses are official organ donors. That leaves a large number of people in the middle who are conceptually in agreement with the idea but haven't officially checked the box to make their wishes known.

"It's an awkward and difficult conversation to have about what will happen to you after you die, and the department of motor vehicles is a particularly difficult environment in which to ask people to make important decisions about their lives," Cameron says. "But Facebook, where you are already sharing your wishes and thoughts and likes with your friends and loved ones, may be a natural place to share your feelings about organ donation. This application will make having that conversation even easier."

In a blog post this morning, Sandberg and Facebook CEO Mark Zuckerberg say that adding a tool to share organ donor status is another step in the evolution of the social network into a powerful vehicle for communication and problem solving.

"As this happens, we hope to build tools that help people transform the way we all solve worldwide social problems," they write. "Medical experts believe that broader awareness about organ donation could go a long way toward solving this crisis. And we believe that by simply telling people that you're an organ donor, the power of sharing and connection can play an important role."

The organ donor status will be part of Facebook's new Timeline feature, which asks users to share stories and photographs from their earliest days. Facebook is now making it easier for users to get more information about donation - including the myths and misperceptions associated with organ donation - and is offering links to state databases where users can make their desire to donate official, just as if they had checked the box at the department of motor vehicles.

"I can't tell you how many times a family, faced with the death of a loved one, says they wished they had asked about organ donation before that person died," Cameron says. He and a team at Johns Hopkins intend to carefully study the effect the Facebook effort has on organ donation rates. If it is successful, Cameron says he believes it could be used as a prototype for tackling other challenging public health problems.

"Getting people to donate their organs has been an intractable public health problem. It stands in contrast to other public health campaigns such as seat belts or drunk driving, which have had major impacts," he says. "If we succeed on Facebook with organ donation, it could be a model for how to use of-the-moment social media to solve important medical issues."